The development of mobile communication technology in recent years has led to rapid spread of portable radio communication devices. Under these circumstances, in order to meet various needs of users, manufacturers of portable radio communication devices have brought portable radio communication devices having a wide variety of forms to market.
In particular, recently, a technique for realizing connection to the Internet and the like through potable radio communication devices has been developed, and this has led to a user's strong demand for an increase in monitor size. In order to meet this demand, a folding portable radio communication device has been proposed which comprises a body divided into an upper body and a lower body which have been linked to each other through a connection called “hinge”, so as to be mutually swingable.
This folding portable radio communication device can ensure a large area of an operating part as an interface with users and a large area of a display for supplying letters or other information to users and, in addition, when it is not in use, can be folded to save the space. Further, a design is possible wherein, when the body is unfolded in use, the spacing between a microphone and a receiver is close to the spacing between an ear and a mouth of a human. This can advantageously realize the provision of good communication quality at the time of calling. Therefore, this type of portable radio communication devices have ensured a great demand as a device which can satisfactorily meet the above needs.
In order to display a larger amount of information obtained through the Internet, there is an ever-increasing tendency toward an increase in size of a liquid crystal display (LCD) screen constituting the display and a change from a black-and-white screen to a color screen. In this case, however, regarding the portable radio communication device per se, there is a tendency toward a reduction in thickness and a reduction in weight for carrying convenience.
In portable radio communication devices, an antenna for radio communication purposes should be provided. A whip antenna, which can be stretched and housed and thus is convenient for carrying, has been widely used. In use of the portable radio communication device, the whip antenna is stretched, while, when the portable radio communication device is in a standby state, the whip antenna is housed within the portable radio communication device. In this case, since communication with a base station is often carried out even in the standby state, even when the antenna is in the housed state, the front portion of the antenna is in the state of projection from the portable radio communication device.
The constitution of an example of this type of folding portable radio communication device is shown in FIG. 1.
The conventional folding portable radio communication device shown in FIG. 1 comprises an upper body 1 and a lower body 2. The upper body 1 comprises a front part 3 of the upper body and a back part 4 of the upper body which have an identical size and have been put on top of each other. The lower body 2 comprises a front part 5 of the lower body and a back part 6 of the lower body which have an identical size and have been put on top of each other. An antenna part 12 comprised of a whip antenna is disposed, at an upper end of the back part 4 of the upper body 1, in the state of projection from the upper body 1. The antenna part 12 can be further stretched toward the outside of the upper body 1 and, in addition, can be housed within the upper body 1. An antenna housing part 24 is provided, within the upper body 1, as a space for allowing the antenna part 12 to be retracted into the upper body 1.
An upper body circuit board 8, an upper body circuit 10, a receiver 15, a display 20, and a power supply terminal 13 for supplying electric power to the antenna part 12 are housed within the upper body 1.
Further, a battery 7, a lower body circuit board 9, a lower body circuit 11, a microphone 16, a key operating part 17, and an external interface 21 are housed within the lower body 2.
The upper body 1 and the lower body 2 are connected to each other through a hinge 19 so that they are mutually swingable and can be folded and unfolded. FIG. 1 is a diagram showing the unfolded state of the upper body 1 and the lower body 2.
In this folding portable radio communication device, the battery 7 is disposed in the lower body 2 from the viewpoints of weight balance at the time of holding of the folding portable radio communication device and stability when the folding portable radio communication device is placed on a desk.
The lower body circuit 11 including a transmitter (not shown) having the largest power consumption is preferably provided at a position close to the battery 7 from the viewpoint of reducing the voltage drop in each power supply pattern. For this reason, the lower body circuit 11 is disposed within the lower body 2. Further, the provision of the lower body circuit 11 within the lower body 2 is also convenient from the viewpoint of a reduction in thickness of the folding portable radio communication device.
The upper body circuit board 8 and the lower body circuit board 9 are electrically connected to each other through a connection 18, having a predetermined conductor pattern between the upper and lower circuits. Signals are transmitted and received through the connection 18 between the upper and lower circuits. The battery 7 is connected to the lower body circuit board 9 and functions to supply electric power to each component part through the lower body circuit board 9.
The connection 18 between the upper and lower circuits is in many cases constituted, for example, by a flexible printed board. The flexible printed board is used for avoiding the breakage of the connection 18 between the upper and lower circuits as the conductor upon swinging of the upper body 1 and the lower body 2 in the hinge 19.
In the conventional folding portable radio communication device shown in FIG. 1, the front part 3 of the upper body and the front part 5 of the lower body are formed of a metal from the viewpoint of ensuring strength.
On the other hand, the antenna part 12 is disposed at the back part 4 of the upper body and is in contact with and connected to a power supply terminal 13 provided in the upper body circuit 10. Further, this power supply terminal 13 is connected to a coaxial cable 25. The coaxial cable 25 is extended from the power supply terminal 13 through the hinge 19 and is connected to the lower body circuit 11. This permits transmission/reception between the power supply terminal 13 and the lower body circuit 11 through the coaxial cable 25. This coaxial cable 25 is fixed to a predetermined position by a cable brace not shown.
FIG. 2 is a front view of the folding portable radio communication device shown in FIG. 1, FIG. 3 a cross-sectional view taken on line A—A of FIG. 2, and FIG. 4 a cross-sectional view taken an line B—B of FIG. 2. FIGS. 3A and 4A each are a cross-sectional view of the folding portable radio communication device in an unfolded state, and FIGS. 3B and 4B each are a cross-sectional view of the folding portable radio communication device in a folded state.
In the conventional folding portable radio communication device, since the antenna part 12 is disposed in the upper body 1, an antenna housing part 24 should be provided, within the upper body 1, as a space for housing the antenna part 12 in the upper body 1. For this reason, in the folding portable radio communication device having this structure, reducing the thickness of the body in the folded state causes the antenna part 12 to be relatively projected from the back part 4 of the upper body.
As a result, although a significant reduction in size of the antenna cannot be realized, a reduction in size and a reduction in weight of portable radio communication devices have been made and, in addition, the size of the display 20 has been increased. Due to this construction, when the antenna part 12 is housed, the antenna housing part 24 is further projected from the back part 4 of the upper body. This is an obstacle to a reduction in size and, at the same time deteriorates the appearance and reduces the degree of freedom in design.
For example, a folding portable radio communication device, wherein an antenna part 12 has been mounted on the lower body 2 side as shown in FIG. 5, is considered effective for reducing the above problem.
Since, however, actual voice speech is carried out in such a state that the lower body 2 is held by the hand, when the antenna part 12 is mounted in the lower body 2 as shown in FIG. 5, the user's hand touches the antenna part 12. This disadvantageously deteriorates the characteristics of the antenna in the antenna part 12.
Further, there is no difference in the level of projection of the antenna part 12 in the housed state between when the antenna part 12 is mounted in the upper body 1 and when the antenna part 12 is mounted in the lower body 2. This poses a problem that, for example, when the user takes the folding portable radio communication device out of a pocket or the like, the antenna part 12 is caught.
Further, since the antenna part 12 comprising a whip antenna is projected from the upper body 1 or the lower body 2, when the portable radio communication device has been accidentally dropped from the whip antenna side, an impact is applied to the whip antenna, disadvantageously often leading to the breakage of the antenna part 12.
Further, in the structure of the conventional folding portable radio communication device shown in FIG. 1, a coaxial cable 25 should be provided for connecting the antenna part 12 to the lower body circuit 11. This poses a problem that the assembly efficiency in the production process is inferior to that in the case of non-folding portable radio communication devices.